Methods of coating a surface and articles with coated surface

Abstract

A method of coating a surface is provided. The method comprises feeding a feedstock to a thermal spray torch, the feedstock comprising a liquid, disposing the feedstock on a substrate by thermal spray under conditions selected to produce a textured surface comprising a hierarchical structure, wherein the hierarchical structure comprises agglomerations of at least partially melted and solidified particles derived from the feedstock with individual at least partially melted and solidified particles derived from the feedstock disposed on a surface of the agglomerations; and applying a surface energy modification material over the textured surface. An article comprising a component having a coated surface is also provided.

1 . A method comprising:
 feeding a feedstock to a thermal spray torch, the feedstock comprising a liquid;   disposing the feedstock on a substrate by thermal spray under conditions selected to produce a textured surface comprising a hierarchical structure, wherein the hierarchical structure comprises agglomerations of at least partially melted and solidified particles derived from the feedstock with individual at least partially melted and solidified particles derived from the feedstock disposed on a surface of the agglomerations; and   applying a surface energy modification material over the textured surface.   
     
     
         2 . The method of  claim 1 , wherein the feedstock further comprises a plurality of particles disposed in the liquid, wherein at least 50% of the particles in the plurality have a diameter less than about 5 microns. 
     
     
         3 . The method of  claim 1 , wherein the feedstock further comprises a plurality of particles disposed in the liquid, wherein at least 50% of the particles in the plurality have a diameter less than about 2 microns. 
     
     
         4 . The method of  claim 2 , wherein the feedstock comprises a ceramic, a metal, a polymer, or combinations thereof. 
     
     
         5 . The method of  claim 4 , wherein the ceramic material comprises an oxide, a nitride, a carbide, or combinations thereof. 
     
     
         6 . The method of  claim 4 , wherein the ceramic comprises yttria stabilized zirconia (YSZ), yttrium aluminum garnet (Y 3 Al 5 O 12  or YAG), ytterbium oxide (Yb 2 O 3 ) or combinations thereof. 
     
     
         7 . The method of  claim 1 , wherein a size of the agglomerations is in a range from about 5 μm to 50 μm. 
     
     
         8 . The method of  claim 1 , wherein the agglomerations have a mean height H above a mean surface level of the textured surface of at least about 1 micron. 
     
     
         9 . The method of  claim 1 , wherein a size of the individual at least partially melted and solidified particles disposed on the surface of the agglomerations is less than 5 μm. 
     
     
         10 . The method of  claim 1 , wherein the agglomerations further comprise at least fully melted and re-solidified particles. 
     
     
         11 . The method of  claim 1 , wherein the agglomerations further comprise one or more pores in a range of about 0 to 90%. 
     
     
         12 . The method of  claim 1 , wherein the surface energy modification material is applied on the textured surface discontinuously. 
     
     
         13 . The method of  claim 1 , wherein the surface energy modification material is a low surface energy material. 
     
     
         14 . The method of  claim 13 , wherein the low surface energy material produces a hydrophobic coating on the textured surface to form a contact angle of more than 100°. 
     
     
         15 . The method of  claim 14 , wherein the hydrophobic coating has a sufficient hydrophobicity to develop a contact angle of at least about 130° between the coated surface and a static drop of water disposed on the coated surface. 
     
     
         16 . The method of  claim 14 , wherein the hydrophobic coating has a sufficient hydrophobicity to develop a contact angle of at least about 150° between the coated surface and a static drop of water disposed on the coated surface. 
     
     
         17 . The method of  claim 14 , wherein the hydrophobic coating has a sufficient hydrophobicity to develop a contact angle hysteresis between an advancing contact angle and a receding contact angle of less than 20° between the coated surface and a moving drop of water disposed on the coated surface. 
     
     
         18 . The method of  claim 13 , wherein the low surface energy material comprises an inorganic material, a fluorinated material, a polymer, or combinations thereof. 
     
     
         19 . The method of  claim 18 , wherein the fluorinated material comprises a fluorosilane or a fluoroalkylsilane. 
     
     
         20 . The method of  claim 18 , wherein the polymer comprises at least one material selected from the group consisting of silicones, fluoropolymers, urethanes, acrylates, epoxies, polysilazanes, aliphatic hydrocarbons, polyimides, polycarbonates, polyether imides, polystyrenes, polyolefins, polypropylenes, and polyethylenes. 
     
     
         21 . The method of  claim 13 , wherein the low surface energy material comprises a fluoropolymer, siloxane, silane, alkyl silane, fluoro-silane, fluoro alkyl silane or combinations thereof. 
     
     
         22 . The method of  claim 21 , wherein the fluoro-silane comprises heptadecafluoro-1,1,2,2-tetrahydrodecyl trimethoxysilane. 
     
     
         23 . The method of  claim 1 , wherein the disposing step comprises disposing the feedstock on a substrate by suspension plasma spray process. 
     
     
         24 . The method of  claim 1 , wherein the liquid carrier is an alcohol, water, or a combination thereof. 
     
     
         25 . The method of  claim 1 , wherein a concentration of the particles disposed in the liquid carrier is up to about 50 wt %. 
     
     
         26 . A method of coating a substrate, comprising:
 feeding a feedstock to a thermal spray torch, the feedstock comprising a liquid carrier and a plurality of ceramic particles disposed in the carrier, wherein at least 50% of the particles in the plurality have a diameter less than about 2 microns;   disposing the feedstock on the substrate by a suspension plasma spray process under conditions selected to produce a textured surface comprising a hierarchical structure, wherein the hierarchical structure comprises agglomerations of at least partially melted and solidified ceramic particles derived from the feedstock with individual at least partially melted and solidified particles derived from the feedstock disposed on a surface of the agglomerations; and   applying a low surface energy modification material over the textured surface.   
     
     
         27 . An article, comprising:
 a component having a coated surface comprising a coating, wherein the coating comprises
 a first layer, wherein the first layer comprises a textured surface comprising a hierarchical structure comprising agglomerations of at least partially melted and solidified particles derived from a feedstock with individual at least partially melted and solidified particles derived from the feedstock disposed on a surface of the agglomerations; and 
 a second layer, wherein the second layer comprises a low surface energy material disposed on the textured surface. 
   
     
     
         28 . The article of  claim 27 , wherein the second layer is a hydrophobic coating has a sufficient hydrophobicity to develop a contact angle of at least about 150° between the coated surface and a static drop of water disposed on the coated surface. 
     
     
         29 . The article of  claim 27 , wherein the coated surface comprises both hydrophobic and hydrophilic regions. 
     
     
         30 . The article of  claim 27 , wherein the coating has a thickness in a range from about 300 nanometers to 5 millimeters. 
     
     
         31 . The article of  claim 27 , wherein the component is a condenser tube.